As is known, integrated circuits are used in a wide variety of electronic equipment, including portable, or handheld, devices. Such handheld devices include personal digital assistants (PDA), CD players, MP3 players, DVD players, AM/FM radio, a pager, cellular telephones, computer memory extensions (commonly referred to as a thumb drive), et cetera. Each of these handheld devices includes one or more integrated circuits to provide the functionality of the device. For example, a thumb drive may include an integrated circuit for interfacing with a computer (for example, personal computer, laptop, server, workstation, et cetera) via one of the ports of the computer (for example, Universal Serial Bus, parallel port, et cetera) and at least one other memory integrated circuit (for example, flash memory).
As another example, an MP3 player may include multiple integrated circuits to support the storage and playback of digitally formatted audio (that is, formatted in accordance with the MP3 specification). As is known, one integrated circuit may be used for interfacing with a computer, another integrated circuit for generating a power supply voltage, another for processing the storage and/or playback of the digitally formatted audio data, and still another for rendering the playback of the digitally formatted audio data audible.
Portable electronic devices that include integrated circuits require at least one DC voltage supply and typically require multiple DC voltage supplies. A DC voltage supply may be generated from a battery or from another DC power source (for example, a 5 volt USB power source). To generate a DC voltage supply from a DC voltage (for example, a battery or a 5 volt USB source), the DC voltage is processed in a controlled manner. For example, using one of a plurality of switch mode converter topologies (such as, full bridge, half bridge, buck, or boost), an inductor is charged and discharged at a controlled rate to produce a regulated DC voltage supply from a DC voltage source.
Device power consumption relates to the supply voltage level and/or to the device clock rate. The regulated DC voltage supply is set at a fixed level to accommodate device applications having the greatest processing speed requirements. But setting the DC voltage supply at this level results in unnecessary power consumption for less power-intensive applications.
Devices are increasingly using diverse applications, with each having different power requirements. As an example, an MP3 encode application has a higher power requirement than an MP3 decode application. Although higher power levels can be used to power applications with lower power requirements, an unnecessary drain results on the battery power supply. While it is desirable to adjust the power supply for different power requirements, it can be onerous to do so because of the amount of oversight by the processing device to implement and to verify changes to the power supply output and the settling time of transients incurred by the changes to the power supply output.
Therefore, a need exists for a method and apparatus for power supply adjustment with increased slewing having a minimal processor oversight and improved response to efficiently accommodate power requirements.